Electric switch



July 23, 1957 F. o. KUHN ELECTRIC SWITCH Filed June 29, 1954 INVENTOR. Fran: 0! K'Llhw A TTOENEY United States PatentO ELECTRIC SWITCH Frank 0. Kuhn, Flint, Mich.

Applic'ation June 29;19'54; SerialNo. 440,127

8 Claims. (CL 200'34) The present"invention'relatesto'electric switches and is particularly directed toward a novel switch construction"which has incorporated therein and associated with parts thereof a" time delay mechanism that, when set into operation, actuates the switch after a predetermined interval of timehas elapsed, and which is of the general type shown and claimeddn my prior application, Serial No. 346,655, filed April 3, 1953, now Patent No. 2,735,671, issued'February 21, 1956.

The principal object of this invention is to provide an improved switch of the character setforth which is simple and" substantial in construction, inexpensive to manufacture, and yet highly efficient and practical in use.

Another object of the invention is to provide, in a switch of the character set forth, a novel arrangement ofparts, whereby resilient contact fingers for closing an electrical circuit'are' also utilized to effect a quick movement or asn'ap action to-amovable contact element during electrical disengagement-of the movable contact element with the fingers.

A'furthe'robject' of the invention is'the provision, in a switch of the above-indicated character, a novel manner of adjusting the'length of time to elapse before actuation of the switch.

A still further object of the invention is to provide, in a-switch of" the character set forth, novel constructions and arrangement of parts for effecting an assembly and retention of the parts relative to one another.

It is also "an object of the invention to provide, in a switch as outlined above, a novel mounting for the switch forming a part of the invention.

These, together with various auxiliary features and objects' of theinvention which will later become apparent as the following description proceeds, are attained by the present invention, a preferred embodiment of which has been illustrated, by way of example only, in the accompanying drawing, wherein:

Figure 1 is-a side elevation of the improved-switch;

Figure 2 is a front view of same; 1

Figure 3 isa longitudinal sectiontaken on line 33'of Figure 1;

Figure 4 is a transverse cross section taken on line 4-4 of Figure 1;

Figure 5 is a sectional view somewhat similar to Figure 3 but differs in that it shows the switch in a position with the circuit closed;

Figure 6 is afragmentary sectional view taken on line 6-6 of Figure 2; and

vthroughout the various views, there is indicated by the numeral 10, a cup-shaped casing of Bakelite or other suitable dielectric material having a cylindrical wall 11, a closed end wall 12, and an open end 13 which is closed by a closure plate 14 of material similar to that of said casing. The cylindrical wall 11 at the open end 13 of 2 the casing "isoutwardl'y increased in thickness, as'at 15, and has oppositely arranged notches 16 extending inwardly from its open end into this thickened portion of the wall; In the side edges of the notches 16 and also inwardly from the open end 13 are grooves 17 into which are slidably received the opposite side edges of rectangular terminal plates 18 of a pair of resilient contact fingers 19 positioned within the casing 10. Threaded in and extendingthrough eachof the terminal plates 18 is a terminal screw 20 under the head of which an end of an electric wire, such as shown in Figure 1, is adapted to be clamped.

The closure wall 14-is partially set into the open end 13 of the cylindrical wallll, as shown at 21, for centering and supporting purposes and has a flange 22 thereon which abuts the end of said cylindrical wall and retains the terminal plates'18 in place. Into aligned drilled holes through the flange in the thickened end portion of the cylindrical wall at'intervals spaced from the notches 16, small drive screws or like fasteners 23 are forced for securing. the closure wall to the casing. Concentric with and projecting;outwardlyfrom a flat outer face of the closure wall 14 is a circular boss 24 which has in the cylindrical surface andspaced outwardly from said flat face an annular-grooveZS-into which is partially received a split ring 26-. On the boss-24 between the fiat face of the closure-wall and split ring 25 are clamped, respectively, a resilient washer 27 and a perforated arm 28 of asheet metal angle bracket-29. The other arm 30 of the anglebracket has a number of smaller perforations therein through which screws or like fasteners extend for attachment of the switch-supporting bracket to a surface of'an object. In some instances where the object to which the switch is to beattached is of sheet metal or like construction, such as automobile body parts, the bracket 29 can be dispensed with and-the sheet metal object itself can be perforated to receive the boss 24.

Extending entirely and centrally through the closure wall 14 and boss 24 thereon is a bore 32 into which is slidably received a round rod 33 with knurled surfaces on its opposite endsfor force fitting thereon a knob 34 exteriorly of the casing and a contact element 35 Within the casing. The contact element 35, being movable, has thereona flat end surface 36' adapted to engage the inner surface of the closure wall 14to limit sliding movement of said contact element in one direction; a cylindrical surface 37 joinedto said flat surface at one end and flush with a conical surface 38'at itsother end, both of which are engageable with the resilient contact fingers 19; and a reduced end extension 39 joined to the conical surface and directed toward the closed end Wall 12 of the casing, the purpose'of which will be set forth as the description proceeds.

Like the casing 10 and closure wall 14, the movable contact element 35, with the exception of a current-conducting sleeve or band 40 thereabout, is of dielectric material; thus, engagement of the resilient contact fingers with the metallic band closes a circuit between said fingers, and engagement of the fingers with the dielectric material opens the circuit. The band 40 extends along substantially the entire cylindrical surface 37 and covers a slight annular portion of the conical surface 38 joined to said-cylindrical surface and is arranged relative to the fingers 19 so that a circuit is closed between said fingers during their entire engagement with said cylindrical sur face and during apart of their engagement with said conical surface.

To provide maximum resiliency to the contact fingers 19, they are constructed of current-conducting spring material and with substantially long U-shaped portions 41 extending lengthwise of the casing and with one leg of each connected to and inwardly offset from a terminal plate 18 and the other leg of each provided with an arched or curved free end 42 that contacts the surfaces of the movable contact element 35.

Seated on an annular shoulder 43 in the casing adjacent the closed end 12 thereof is the rim portion of a self-contained time delay mechanism 44 which is of the same general construction shown and claimed in my previously referred-to prior aplication. In order that the construction and operation of the unit 44 and its association with the present invention may be clearly understood, following is a brief description thereof:

The supporting structure of the unit consists of a cap 45 having an outwardly flaring portion 46 terminating in a radially extending peripheral portion 47 whose outer edge has integrally formed therewith a cylindrical flange 48. There is also provided as a part of the unit 44 a circular diaphragm 49 of rubber, neoprene, or the like, having an outwardly extending centrally disposed noselike thickened portion 50 in which is centrally and longitudinally arranged one or more fibrous threads 51 of e nylon or the like. A locking ring 52 of extremely thin fiat metal is positioned over the peripheral potrion of the diaphragm 49 to maintain such peripheral portion against the radial portion 47 of the cap 45, and the ring 52 is locked in position by splitting the flange 48 at circumferentially spaced points to form inwardly directed lugs 53. The ring 52 is chordally cut away, as indicated at 54, to thereby expose a sector 55 of the peripheral portion of the diaphragm 49 and to provide flexibility to an area of the ring, such portion thus becoming an outlet valve for the unit 44.

The inner face of the thickened portion 50 has integrally formed thereon a circular boss 56, and a helical spring 57 interposed between the cap 45 and diaphragm 49 has its smaller end encircling said boss while its larger end bears against said cap.

In the operation of the unit, it will be apparent that the diaphragm 49 may be quickly moved from its extended position, as illustrated in Figure 3, to its collapsed condition, as shown in Figure 5, by pressing inwardly upon the enlarged portion 50 against action of the spring 57. During this inward movement of the diaphragm 49, air will be expelled through the outlet valve 23, it being apparent that the weakened portion of the ring will be flexed outwardly by air being compressed in the unit, and thus, air will escape under the portion of the diaphragm supported by such weakened portion. When air has been thus exhausted from the interior of the unit 44, and inward pressure is released from the other side of the diaphragm, the spring 57 will begin to urge the diaphragm again to its outward position, shown in Figure 3. Such outward movement of the diaphragm would normally be impossible due to atmospheric pressure, it being understood that the spring 57 is of insuflicient strength to overcome such atmospheric pressure. The provision of the thread or threads 51, however, makes it possible for air to pass from without the unit 44 through such threads to the interior of the unit. Due to the minuteness of the diameter of the threads and the length thereof through which such air may pass, the re-introduction of air into the unit necessarily consumes a definite period of time.

The various parts of both the switch structure and unit 44 are arranged and proportioned relative to one another so that when the unit 44 is in its expanded position as shown in Figure 3, the pointed nose-like thickened portion 50 of the diaphragm will be seated in a central recess 58 in the end of the extension 39 of the movable contact element which is held against the closure wall 14 by the resilient contact fingers 19.

While the peripheral portion of the unit 44 normally rests on the shoulder 43 of the casing with the base of the cap 45 in close proximity to the end wall 12 of the casing, a set screw 59 threaded through the wall 12 and engagingthe base of the cap can adjust the unit 44 to a position slightly away from the shoulder 43 so as to effect disengagement of the fingers 19 from the band 37 in a shorter length of time, it being understood that the cylindrical flange 48 on the unit 44 is snugly fitted to the inner surface of the cylindrical wall 11 for frictionally supporting the unit.

The operation of the switch is as follows:

In Figures 1 and 2, the switch is shown in its normal off position, and all that is required to close a circuit between the terminals 20 and set the switch in operation is to manually push the knob 34 inwardly to the position shown in Figure 5 which engages the cylindrical portion of the current-conducting band 40 on the movable contact element 35 with the resilient contact fingers 19 and at the same time collapses the self-expansible time delay unit 44. Upon release of the knob 34, the movable contact element 35 will be held against the slowly expanding time delay unit by pressure of the resilient contact fingers 19 on the cylindrical surface 37 of said movable contact element. This pressure, however, offers very little resistance and is easily overcome by the expansion pressure of the time delay unit which results in timed movement of the movable contact element in accordance with expansion of the time delay unit. Upon arrival of the conical surface 38 of the movable contact element into engagement with the resilient contact fingers 19, and while current is still being conducted between said fingers, the angle of the surfaces to which pressure applied by the fingers causes the fingers to impart a quick or snap movement to said movable contact member in advance of movement by said time delay unit to a position against the closure wall 14 and out of electrical engagement with said fingers. By referring to Figure 3, it will be observed that upon completion of an operation of the switch, the resilient contact fingers 19 remain in engagement with the dielectrical material of the movable contact element and on the conical surface 38 thereof for yieldably retaining the flat end surface 36 of said movable contact element in engagement with the inner surface 21 of the closure wall 14.

While I have herein described a specific form which the invention may take, it will be understood that changes and modifications may be made by those skilled in the art which still fall within the spirit and scope of the appended claims.

What is claimed is:

1. An electric switch including a casing, stationary contacts in said casing, a movable contact element in said casing, a circular boss of reduced size and of dielectric material extending outwardly from a flat surface on said casing, a control member arranged exteriorly of said casing and connected to said movable contact element for manually moving said movable contact element into and out of electrical engagement with said stationary contacts, said circular boss of dielectric material having an annular groove in the cylindrical surface thereof, a

resilient washer on said boss between said flat surface of said casing and said groove, a split ring partially received in said groove, and a supporting member for said switch having an opening therein through which said boss extends and which is clamped between said split ring and said resilient washer.

2. An electric switch including a substantially cupshaped casing of insulation material, a closure wall also of insulation material attached to the open end of said cup-shaped casing, a circular boss of reduced diameter extending outwardly from the outer surface of said closure wall, a pair of spaced resilient contact fingers attached to and arranged in said casing, a rod extended through and slidably supported by said closure wall and saidboss thereon, a contact element insulated from and fixed on the inner end of said rod and within said casing for movement between said resilient contact fingers and into and out of electrical engagement therewith, a time delay self-expansible unit positioned in said casing between the end wall thereof and said contact element for engagement with and movement of said contact element toward a position where it is out of electrical engagement with said fingers, a knob on said rod outwardly of said boss for manually moving said contact element to a position whereby the expansible unit is collapsed and the contact element and resilient contact fingers are electrically engaged, said circular boss having an annular groove in the cylindrical surface thereof, a resilient washer positioned on said boss between said closure wall and said groove, and a split ring partially received in said groove and adapted to clamp a portion of a supporting structure between same and said resilient washer.

3. An electric switch including a casing having a cylindrical wall and an end wall and constructed of insulation material, a closure wall also of insulation material attached to the open end of the cylindrical wall of said casing, a pair of oppositely disposed resilient contact fingers stationarily arranged on said cylindrical wall and within said casing, a time delay self-expansible unit positioned within said casing adjacent the end wall thereof, a movable contact element within said casing and mounted on said closure wall for sliding movement into and out of electrical engagement with said resilient contact fingers and normally held in a position out of electrical engagement with said fingers by expansion of and engagement with said time delay self-expansible unit, and a manual control member arranged exteriorly of said casing and said closure wall and cooperable with said movable contact element for manually sliding said movable contact element to a position where it electrically engages said contact fingers and collapses said time delay self-expansible unit.

4. An electric switch including a casing having a cylindrical wall and an end wall and constructed of insulation material, a closure wall also of insulation material attached to the open end of the cylindrical wall of said casing, a pair of oppositely disposed resilient contact fingers stationarily arranged on said cylindrical wall and within said casing, a time delay self-expansible unit positioned within said casing adjacent the end wall thereof, a movable contact element within said casing and mounted on said closure wall for sliding movement into and out of electrical engagement with said resilient contact fingers and normally held in a position out of electrical engagement with said fingers by expansion of and engagement with said time delay self-expansible unit, adjustable means on said casing and in engagement with said time delay self-expansible unit for adjusting the stationary position of said unit in said casing and relative to said movable contact element, and a manual control member arranged exteriorly of said casing and said closure wall and cooperable with said movable contact element for manually sliding said movable contact element to a position where it electrically engages said contact fingers and collapses said time delay self-expansible unit.

5. An electric switch in accordance with claim 4 wherein the adjustable means for positioning the time delay self-expansible unit in the casing comprises a screw threaded in and extending through the end wall of the casing and in engagement with a non-expansible portion of said time delay self-expansible unit.

6. An electric switch including a substantially cupshaped casing of insulation material, a closure wall also of insulation material attached to the open end of said cup-shaped casing, a pair of spaced resilient contact fingers stationarily arranged within said casing, a time delay selfexpansible unit positioned within said casing adjacent its end wall, a rod extending through and slidably supported by said closure wall, a head of insulation material fixed to the inner end of said rod and arranged within saidcupshaped casing, a cylindrical electric contact band fixed to said head and adapted to be engaged by said resilient contact fingers, a frustum-shaped surface which is formed by a part of said head and by a part of said band and which is also adapted to engage said resilient contact fingers, said insulated head being normally held by expansion of said time delay self-expansible unit in a position with said contact fingers in engagement with the insulated frustum-shaped surface of said head, and a knob on the outer end of said rod for manually moving said head to a position whereby the expansible unit is collapsed and the cylindrical contact band and resilient contact fingers are engaged.

7. An electric switch in accordance with claim 6 wherein an extension is provided on the insulated head and whereby said extension engages the time delay self-expansible unit during the collapsing of said unit and timed movement of the head by said unit.

8. An electric switch including a substantially cupshaped casing of insulation material, a closure wall also of insulating material attached to the open end of said cup-shaped casing, said cup-shaped casing having the cylindrical wall at the open end thereof notched at locations opposite one another and provided with grooves at opposite sides of the notches, a pair of oppositely disposed resilient contact fingers arranged in said cup-shaped casing and supported in position by having opposite edge portions thereof received in said grooves and by engage ment of said closure wall therewith, terminal connections on said fingers at locations within said notches, a time delay self-expansible unit positioned within said casing adjacent the end wall thereof, a movable contact element within said casing and mounted on said closure wall for sliding movement into and out of electrical engagement with said resilient fingers and normally held in a position out of the electrical engagement with said fingers by expansion of said time delay self-expansible unit, and a manual control member arranged exteriorly of said casing and said closure wall and connected to said movable contact element for manually sliding said movable contact element to a position where it electrically engages said contact fingers and collapses said time delay self-expansible unit.

References Cited in the file of this patent UNITED STATES PATENTS 1,169,089 Lawton et a1. Jan. 18, 1916 1,448,058 Eis et a1 Mar. 13, 1923 2,306,877 Gould Dec. 29, 1942 2,488,982 Mekelburg Nov. 22, 1949 2,579,168 Ballou Dec. 18, 1951 2,584,477 Lindenmuth Feb. 5, 1952 2,640,295 Auler et al. June 2, 1953 2,669,616 Frank Feb. 16, 1954 

